As to a method of ejecting a liquid of ink or the like, there is known a method of using an ejection energy-generating element such as a heat generating element (heater) or the like to bring a liquid to a boil to generate an air bubble, a pressure of which causes a liquid drop to be ejected from an ejection opening in the print head. In regard to such a liquid drop ejecting method, there are provided a bubble through jet (hereinafter, called also BTJ) ejection method in which an air bubble in the print head is communicated with the atmosphere in the liquid drop ejection process and a bubble jet ejection method in which the air bubble in the print head is not communicated with the atmosphere in the liquid drop ejection process. FIG. 8A to FIG. 8H are pattern diagrams showing a general ejection process in the BTJ ejection method by using a cross-section of the ejection opening vicinity in the print head.
According to the liquid ejection method, when a liquid to be ejected in the liquid drop ejection process is separated from the liquid in the print head to form a liquid drop, there may possibly occur a phenomenon where the separated liquid drop is divided into a liquid drop (hereinafter, called a main drop) which should be originally used for printing and a side liquid drop (hereinafter, called a satellite). There are some cases where degradation of image quality is caused by the event that the satellite lands on a print medium at a large distance from the main drop or the satellite loses its speed before reaching the print medium to be formed as a floating liquid drop (hereinafter, called a mist), possibly causing contamination of the print medium.
For a reduction of the satellite, for example, as described in Japanese Patent Laid-Open No. 2008-290380 or the like, it is known to shorten a length of an ink tail (tail of a liquid extending in a columnar shape) in the liquid drop to be ejected. Japanese Patent Laid-Open No. 2008-290380 discloses a technology that an ejection opening is provided with a projection projecting inside thereof to limit an amount of the liquid involved in the ink tail, whereby the length of the ink tail is shortened to reduce the satellite.